High Frequency Currents and Apparata

(Concluded)

AT Fig. 7 is shown how a 16-cp. 110-
volt incandescent lamp may be
lighted through the body by a
high frequency coil. A piece of copper
wire is firmly held in the mouth
for this somewhat startling experiment and
it is also joined to one terminal of the incandescent
lamp. A second wire is connected from the other terminal of the lamp to the high frequency transformer.

When the proper adjustments have been
made on the high frequency set it will be
found possible to bring the lamp up to full
brilliancy. The Oudin connections are invariably
employed for this class of experiments
where lamps are lighted, sparks allowed to jump to the hand, etc. A word
of caution should be mentioned here, as
these high frequency sparks will burn
considerably when allowed to jump directly to
the skin. In any case, a piece of metal
should be held in the hand. No severe shock
is experienced in the passage of such high
frequency currents through the body as
long as they are properly handled by allowing
the spark to enter the body through
a metal electrode, as stated, and providing
the frequency is high enough. Experiments
have been conducted where half a
million volts were passed through a man's
body with several amperes of current.

Even with a small high frequency set, lighting
a 32-cp., 110-volt lamp, then one ampere
of current is passing through the body.
With this current, as indicated on a hotwire
ammeter (and which also has the effective
current value of one ampere), it is
quite possible that it may have an instantaneous
maximum value of as much as 160
to 170 amperes. This is due to the very
rapid discharge of the condensers in the
circuit, and if large enough electrodes are
used on the skin no burning effect will be
felt.

Rather spectacular high frequency discharge
effects are portrayed at 8 and 9.
These are usually produced by using an
Oudin transformer giving a powerful unipolar
discharge at high frequency and
ultra-high potential. In the experiment at
Fig. 9 a metal piece is held in the hand
and a flame discharge from same leaps
forth into space. The body of the man is
here charged at very high voltage by connecting
the high frequency terminal of the
Oudin transformer to his ankles through a
couple of metal ankle straps. He is best
seated on a glass platform for this experiment,
and all of the adjustments in the
high frequency transformer circuit must be
very carefully made in order to produce
these fine effects, and the inductance of the
primary exciting transformer is very important.

It is quite advisable, and in fact
imperative in some experiments of this
nature, to use an adjustable impedance coil
in the primary of the exciting step-up
transformer, so as to be able to tune it
properly with respect to the high frequency
circuit. The wonderful effect produced at
Fig. 8 is also an Oudin coil phenomenon,
and a very tine spray is seen to branch out
all around the top of the high frequency
coil. This effect is truly marvelous and can
only be fully appreciated when observed at
first hand. No photograph, and especially
a half-tone as here printed, can do justice
to the weird and awe-inspiring effect produced
in this way. In this experiment a
person can approach carefully the highly
charged Oudin coil and part of the spray
will discharge through the head without
any appreciable shock as long as the person
does not come too close.

In the electro-therapeutical application
of high frequency currents by the medical
profession there is often employed a large
wire cage of sufficient size to enclose the
subject's body as Fig. 10 shows. The high
frequency current from an Oudin or Tesla
machine is passed through this large helix
and powerful currents are induced in the
subject's body, and in this way are produced
valuable results of an electro-therapeutical
nature for various kinds of ailments
and diseases. This method is one
of the best known to medical science for
the treatment of arteriosclerosis, or as it
is commonly termed, "hardening of the
arteries." Dr. D'Arsonval, the noted French
scientist, has made numerous measurements
in this direction and has proved by
tests on different male and female patients
that, after a few treatments of this kind,
the blood pressure can be reduced quite
markedly, and in most cases permanent
lowering of arterial blood pressure is effected.

This large solenoid arrangement can be
used to produce spectacular high frequency
stunts and experiments, a common one being
to let the person inside of the wire
cage hold a Geissler tube in his hands so
that the current produced in the body will
pass through the tube from one hand to
the other, lighting up same in a spectacular
manner. If the cage is made sufficiently
large, two or more persons may stand
within same and Geissler tubes placed in
their hands so as to complete the circuit
from one body, through a Geissler tube, to
the next body, etc., giving a very interesting
effect for stage and lecture purposes.

Many other remarkable and interesting
experiments with high frequency currents
will be found described in the series of
many excellent books listed at the end of
this discourse. It can also be said that we
of to-day know very little about these high
frequency currents and their possibilities.

Nikola Tesla has done more in this direction
than any other person, as can be readily judged
from the fact that over 15 years ago he
successfully produced sparks 100 feet long
resembling in volume and sound the lightning
discharges we have all seen in nature
(not imitation ones). It is hoped that this
article may serve to kindle the spirit of
research along these lines in the young experimenter's
mind, and he surely will be
amply rewarded for any discoveries he may
make in this little-understood branch of
electrical science, which bids fair to unlock
the door to a future electrical era of which
our generation has no reasonable conception
at this time.